Saturday, July 5, 2014

Using guidelines? Think carefully

Guidelines are meant to help the doctor deal with an
individual patient but they are based on information obtained from groups
of patients. Description of groups has to rely on statistics using averages
to describe various characteristics and results.

When you apply the results of various medical
interventions obtained in a group (frequently in the thousands) to your
individual patient, you are presuming that your patient is similar to the
patients in the group so that you expect him to respond to the treatment
in a similar way to that of the group. But the response of different
patients in the group is not the same. You do not know the characteristics
of various individuals in the group and how each one responded. What you
may know is the averages of their characteristics and the averages of
their responses. Those who wrote the guidelines for you based their
guidelines on these.

The critical question then is whether your patient
is sufficiently similar to the average of the group (or the groups)
studied so that you can reasonably apply the guidelines to him.

This can best be explained by an example.
Guidelines on the treatment of non valvular atrial fibrillation using CHAD or
CHADS2 score lump together patients with permanent atrial fibrillation and
patients with paroxysmal atrial fibrillation. Treating the two types
similarly is based on studies that showed similar prognosis regarding
their liability to develop strokes. The cause of this is not clear but it
may be related to the fact that the patient with paroxysmal fibrillation
is more prone to develop a stroke
when fibrillation reverts to sinus rhythm and this may offset his decreased
risk when he is in sinus rhythm. The vital question is this: are we
justified to treat a patient who has two or three attacks a year each
lasting several minutes in the same way as a patient who has daily (or
every few days) attacks each lasting many hours because both patients
carry the same label of paroxysmal fibrillation?!

Applying guidelines to your patient without
considering his individual characteristics and circumstances is like a
tailor who, when asked to make a suit for an Iraqi man, does not take his
measures; instead he makes the suit relying on statistical figures
describing the physical characteristics of Iraqi men. If the man happened
to be much taller (or shorter) than the average Iraqi, it is just bad
luck!

This does not mean that we should not use guidelines
but that we should take into consideration the individual characteristics
and circumstances of the patient we are treating. You should ask yourself
whether your patient is sufficiently similar to the average patient with
that condition to justify applying the guidelines in his case. If not, you
should modify your application of the guidelines according to your
judgment of the magnitude of the difference.